Molecular characterization epidemiology and management of tomato leaf curl virus tolcv in northern Karnataka

Abstract

Tomato leaf curl virus (ToLCV) disease is one of the most important viral diseases of newlinetomato and causes substantial losses every year. Survey results revealed that ToLCV was newlinepresent in all the fields visited in Belgaum, Dharwad, Gadag and Haveri districts. The disease newlineincidence ranged from 4-00 per cent during rabi 2005 and 60-100 per cent in summer 2006. newlineA few natural weed hosts viz., Parthenium hysterophorus (Parthenium), Euphorbia geniculata newline(Bhedi soppu), Ageratum conyzoides (Oorala gida), Acanthospermum hispidum (Kadale newlinemullu), Blainvillea rhomboidea (Ervapalha) Cass. and Lachnera pusilla L. showed positive for newlineToLCV infection in the PCR detection. newlineThe results of the cloning and nucleotide sequencing of the coat protein gene newlinerevealed that isolates from Belgaum, Dharwad and Haveri showed 95.10 to 99.60 per cent newlinehomology indicating they are closely related to each other. However, these isolates showed newlinewide variation of upto 46.50 per cent divergence with some of the isolates of North Western newlineIndian ToLCV 17 Nasik (AJ 10356) and North Indian ToLCV 19.Patna (AJ 810358). newlineThe survey, bioassay and RAPD-PCR analysis of whitefly vector revealed the newlineprevalence of Bemisia tabaci-B-biotype in addition to the indigenous type in Dharwad region. newlineTomato planted during August and November showed slow progress of the disease and less newlineincidence as there was high humidity and high rainfall, which suppress the vector activities newlinewhereas, maximum incidence was recorded in February and May planted crop. newlineIn the management of disease the sequential application of Imidachloprid (0.005%) - newlineTriazophos (0.15%) Thiamethaxam (0.05%)-Econeem (0.5%) found effective with low newlinedisease incidence and better yield. The Clerodendron inermis and Glyricidia leaf extract newlineapplication also found effective. In the field screening cultivars such as Nandi, Vybhav, newlineSankranti, and hybrids Utsav, HY 558, HY 530, NS-719 and NS-563 showed resistance newlinereaction and the commonly cultivated Megha showed susceptible reaction. newline